Conventionally, a technique called FIB-SEM, as illustrated in FIG. 4, has been known as a technique for evaluating the state of dispersion of a filler in a polymer material containing a polymer compound and the filler. In the technique as illustrated, first, (a) a polymer material 1 is irradiated with a focused ion beam (FIB) 10 in a perpendicular direction; and (b) the surface of the polymer material 1 is cut. Then, (c) a smooth cut surface 1B which is parallel to a beam direction in the cut surface formed by the cutting is photographed by a scanning electron microscope (SEM), and the state of dispersion of the filler is evaluated by observing an obtained image. A technique called 3D-TEM as illustrated in FIG. 5 is also known.
In the above, FIB-SEM is a technology that is frequently used for, e.g., the cross-section observation of the wiring situation of a semiconductor; and, in this case, since the resolution of the semiconductor in its thickness direction is very important, it is necessary to irradiate the semiconductor with FIB in the thickness direction. Further, for example, Patent Document 1 discloses, as an improved technology for a method for observing the state of dispersion of a silica blended in a silicone rubber by an electron microscope, a method for observing dispersion of a silica in a silicone rubber, comprising: freezing and curing a molded product of a silicone rubber blended with a silica; then tearing the product to make a sample; and observing the torn surface of the sample by a scanning electron microscope set at a low acceleration voltage of 10 kV or less.